I've been looking at the representation of steam propulsion in SOG for a while, mainly with the Opium Wars and the Crimean War in mind. Standard manoeuvre decks would work fine, ignore wind direction and effects and select "low", "medium" or "high" throttle settings equating to sail settings to reflect varying engine power settings )or just use the current approach to altering sail settings as is and simply apply to the engines). Ships with lower power engines could be restricted in the throttle setting they could use.

"Broken mast" damage could then be applied to engine power, each level reducing the ships maximum power level by one.

Thats as far as I've got so far, thoughts and comments welcomed :)